Power Management in a WLAN Infrastructure

1. A method for managing power consumption in a wireless local area network having multiple access points with overlapping coverage, where modes of different power consumption are available to the access points, the method comprising: assessing whether the traffic load of the network can be adequately supported using fewer access points in an active mode; if the traffic load can be adequately supported using fewer access points in the active mode, redistributing the traffic load from certain active access points among the remaining access points in the active mode and switching the certain access points into a mode of lower power consumption than the active mode.

2. The method of claim 1 , wherein redistributing the traffic load and switching the certain access points into the lower-power-consumption mode comprises: each of the certain access points independently determining to disassociate mobile stations to reduce its own load and to switch into the lower-power-consumption mode.

3. The method of claim 1 , wherein redistributing the traffic load comprises using load balancing.

4. The method of claim 1 , wherein assessing whether the traffic load can be adequately supported using a reduced number of access points in the active mode comprises: assessing the usage for each individual access point; and communicating the individual usages to all the access points in the network.

5. The method of claim 4 , further comprising: calculating a mean value of the usages for all the access points in the network; and determining that the traffic load can be adequately supported if the mean value does not exceed a maximum allowable value.

6. The method of claim 4 , wherein the usage is the usage during times reserved for best effort traffic.

7. The method of claim 6 , further comprising: assessing the connection oriented usage for each individual access point; and communicating the individual connection oriented usages to all the access points in the network.

8. The method of claim 7 , wherein redistributing the traffic load comprises: redistributing the traffic load by first transferring mobile stations that are supporting only best effort traffic from an overloaded access point to other access points that are in the active mode; and thereafter transferring mobile stations that are supporting both best effort traffic and connection oriented traffic from an overloaded access point to other access points that are in the active mode only if transferring the mobile stations that are supporting only best effort traffic did not redistribute the traffic load sufficiently.

9. The method of claim 1 , wherein assessing whether the traffic load can be adequately supported using a reduced number of access points in the active mode comprises: calculating the battery capacity level for each individual access point; and communicating the individual battery capacity levels to all the access points in the network.

10. The method of claim 9 , further comprising: comparing the battery capacity levels to identify the access point in the active mode which has the lowest battery capacity level.

11. The method of claim 10 , wherein the certain access points include the access point in the active mode which has the lowest battery capacity level.

12. A method for managing power consumption in a wireless local area network comprising multiple access points with overlapping coverage, where modes of different power consumption are available to the access points, the method comprising: assessing whether the traffic load of the network is adequately supported by the current number of access points in an active mode; if the traffic load is not adequately supported by the current number of access points in the active mode, switching to the active mode certain access points which are in a mode of lower power consumption than the active mode and redistributing the traffic load among the access points in the active mode including the certain access points.

13. The method of claim 12 , wherein switching certain access points to the active mode comprises: each of the certain access points independently determining to switch into the active mode.

14. The method of claim 12 , wherein redistributing the traffic load comprises using load balancing.

15. The method of claim 12 , wherein assessing whether the traffic load is adequately supported by the current number of access points in the active mode comprises: assessing the usage for each individual access point; and communicating the individual usages to all the access points in the network.

16. The method of claim 15 , further comprising: calculating a mean value of the usages for all the access points in the network; and determining that the traffic load is not adequately supported if the mean value exceeds a maximum allowable value.

17. The method of claim 15 , wherein the usage is the usage during times reserved for best effort traffic.

18. The method of claim 12 , wherein assessing whether the traffic load is adequately supported by the current number of access points in the active mode comprises: calculating the battery capacity level for each individual access point; and communicating the individual battery capacity levels to all the access points in the network.

19. The method of claim 18 , further comprising: comparing the battery capacity levels to identify the access point in the lower-power-consumption mode which has the highest battery capacity level.

20. The method of claim 19 , wherein the certain access points include the access point in the lower-power-consumption mode which has the highest battery capacity level.